Joint for tubular furniture frames



NOV. 20, 195] SHQTT 2,576,049

JOINT FOR TUBULAR FURNITURE FRAMES Filed 0012. 15, 1949 IN VEN TOR.

mwrsw BY AMQ4 MY M ATTORNEYS Patented Nov. 20, 1951 JOINT FOR TUBULAR FURNITURE FRAMES Allen T. Shott, Cincinnati, Ohio, assignor to Balcrank, Inc., Cincinnati, Ohio, a corporation of Ohio Application October 13, 1949, Serial No. 121,130

Claims.

This invention is directed to tubular metal furniture and is addressed particularly to a new and improved joint for detachably interconnecting various tubular members which form the frame. In order to simplify the disclosure, the invention will be discussed herein in relation to metal chairs, but those skilled in the art will readily appreciate that the invention may be employed in the fabrication of racks, metal tables and articles of similar nature.

A typical tubular steel chair frame comprises a base upon which the chair is supported, legs which rise from the base to elevate and support the seat, and arm rests which extend between the seat and the back. Since the shape of such a frame is unwieldy and awkward for storage and shipping purposes, it is desirable to fabricate the frame from a number of sections which are detachably joined together and which may be complexity which change in character and magnitude as the occupant rocks back and forth and shifts from side to side. If the frame joints are not sufficiently strong and rigid to withstand these forces without yielding or loosening, the frame becomes misaligned and the joints become loose. Under these conditions, the chair sags weakly and wobbles from side to side or weaves, in response to the shifting weight of the occupant.

The rounded configuration of the tube walls makes it particularly difficult to connect adjoining tubular sections in a firm, rigid joint, especially when the sections are disposed in angular relationship to each other. It is extremely difficult to form a stable mechanical interlock between the rounded tube walls, and the sections consequently tend to roll or shift out of angular alignment under stress even when they are supported by bolts fastened through the adjoining sections. Moreover, the flat nut and bolt heads do not seat firmly on the curved wall surfaces, and they too tend to loosen for lack of sufficient frictional contact surface with the tube walls. This problem is particularly acute in the frame base where the most critical joints are located. When these joints, which are subjected to the most severe and complex stresses, work loose, the initial misalignment is multiplied throughout the frame with the result that other stresses are imposed on the other joints of the frame and these, therefore, soon also become loosened. In my copending patent application for Chair Structure, Serial No. 14,541, filed March. 12, 1948, I have disclosed and claimed an improved joint for articulating the tubular sections which form the base of the chair. The present invention is directed to an improvement over the joint disclosed in that application. The object of this invention is to provide stable, rigid joint for tubular frame sections which is capable of withstanding the severe complex stresses imposed on and transmitted by the frame without yielding or loosening. The joint of this invention is particularly adapted to prevent angular displacement of the adjoining frame sections relative to each other, but it also includes improved means for strengthening the frame sections against the longitudinal, transverse, rolling and twisting stresses which tend to part them. i

It is a further object of the invention to provide an inexpensive joint which can be quickly and easily manufactured and is susceptible to assembly and disassembly by persons having the most meager mechanical Skill. 7

In recognition of these objectives, the invention contemplates a joint for adjoining tubular frame sections which comprises mechanically interlocking tabs formed respectively on. the section ends, which are configurated and dimensioned to abide in mutually supporting, nested relationship, and means for detachably holding said tabs in firm mechanical and frictional en'- gagement with each other. Each tab forms a seat or saddle for the other tab and is provided with a pair of abutments which cooperate with the abutments on the other tab to prevent angu: lar displacement of the sections relative to each other and absorb and distribute tension, compression and torsional forces which otherwise would tend to rupture or loosen the joint. Pref erably, the tabs are integral with the tubular body of the section and they can be formed quite inexpensively by collapsing or deforming the end portions of the tube side walls in a single step forming operation.

Other advantages of the invention will become apparent to those skilled in the art from the following detailed description of the drawings in which:

Figure 1 is a side elevation of a typical chair including a tubular frame in which a preferred is included.

tion may include a sheet metal back I0 and a 5 sheet metal seat H which are joined together by bolts (not shown) at the rear of the seat. A tu bular steel frame, indicated generally at l2, r e-M siliently supports the chair and permitsa gentle rocker-line action when the occupant shifts his weight by alternately leaning backward and fore ward in the seat.

In order to facilitate shipment and storage the frame I2 is divided into sections which can be disassembled and compactly packaged in relatively narrow. cartons. .I-Ienoe, thewfljam 90mprises-a pairloftsidelsectionsJ 3. (only oneof which is shown)v and a. crosstarmwlA connectin the side sectionspat. therearhof the {chair-base. The side sections 1.3 t are. substantially identical. and Whi only .one is showninFiguzre it is apparentthat a similar element, is fixed onthe ther. i Of h chain; Each .side memberllii; providesan arm rest. 15,: bolted to thewbackt of the chair as; at i 6, aleg H1. boltedtotheseat of the chair and a baseumemben l8 .which..contacts the fl r and formsa lJeshaped, basein conjunction with the othenhasemember. isandthelcross. arm Hi Th endshof the crossarmareconnected to the ends ofrthexbasetmembers .throusha a s nr tia1ly...identica1joints; oneof which is shown enerallmo-atllfltin Figure 1. This chair may be disassembledlbx di co nect n t e eat nd he k pieces, unscrewing the bolts which. connect the side nieoesstdthe back; and sea and di n e i ath joints! 0,

. The. detailed c nst uction f i t i shQwnX'inQFigure sZ and 3, Itwill be observed that the end portions, Qf,;t,he ,cro ss arm andthe basesectionhavebeen .configurated into, substantiallyhfiattenedtabs, 4 Inthe mbodiment. shown thel-endrviselp r i nhof m m r, 8 s is -sha ed longitndina lyhbut is. ubstan ia l rai ht n o ion; The endw e p rt on e cross arm .;,1fs. cl. h-s ne n r se t on ut is ubst n ial y: rai ht on it ine 7 h a 2L0 the end of th e cross arm [6 is adapted to sting relationship with tab 22 on the end of thesbase'section B8. The tabs are held firmly position by meansof two bolts 23 whieh extendjthrough holes (not shown) in both tabs andar'e secured in position by nuts 24;

The tabs which are of double walled thickness may be constructed by deforming or collapsing the side Walls of the tubular sections by a singlethe sections about the joint by abutting the ears 26 and 21.

It will be observed from inspection of Figure 3 that tab 22 does not reside in the plane of the axis of base member l8 but is ofiset to receive the tab 2! which resides in the plane of the axis of the cross arm [4, thereby permitting the cross arm and the member; I 8'to'be;disposed in the same plane andabut the floorevenly. 'This type of construction is discussed in my co-pending patent application previously referred to, to which attention is invited. However, in the present instance this construction provides an unusual advantagesince apronounced abutment 2B is formed between-the main body of the element [8 of tab 22. This abutment extends transversely along the length of ,ear. 26 contacting and supporting the earl The other edge of tab 22 is upturned tohzprovide an abutment lip 29 which extends transversely across the tab and supports the nsthor e rztq 7 Home tab 2 s fi mly" supp r ed. b tween mee t ve; a utments. onthe o po ite. endsroi tab Handle n fac W e he vi t em whenthe bol s. re ul y i h ened, lt w lbe obse vedtha if s re sosappliedto he iointare sucnthatthe fi n t o or o he secti ns 42. nd. t ana -11amin re ation to, eoh. o her the. moments-.28 an 2.9 Will s stai the andior ven m emen vvof either tab relativ to theothen l lmemb r fisi or d. re rwe d x or. rwardly whileme nben I4 is h ld te ona x b abutment with a ior ien ob,- ta he anathema 2. 5 and 2,9. and the. ear 32.6 anfiflr i leoo e t resi tthe no merit and ebsq h, en d stri ute-t e stre ses other: ould net- 9 h erz o bolts. On theother hand, f. member-As ta i nar n r ss arm 1. orc dlaterauv outwar elativetolit, the e eefil; mot ully-s ownl o tab Will ontao t e .b ii m n io m ds be we n the underside; of ab Han heho sio orossarm L 1 The, ted re ationship of the curved;.contac area he ,7 vthe take else-tends; toeresistlzand ist ibute he .o: .e. imposed: on; thexiointhwhen the chair; pcupant; leans forward.:and backward hi .9 .9 b ob er ed; that. bendin tres a erimposedzen the; membe .S;;|3j.iil the dir o onoiz h la lowsishpwnlinFigure?. conquout1y,-. arm: L8 tends-.toipivot, ahoufii-lthehjflint in a cordance, ththedireetion oithe bendin stress n the e is, a finfi llfiyLMBdeRV QP ateG flexinaforthejcint t9 work: looses. However, by virtue of this invention, the loosening action-.is

usted.beeausertheburvedocontactlsnra "ib te heforoes; illlllQSGd;QI1-;the-;ioint over euhs ntiai a ea; and. erevent1oca1izedconion li i nqfrztheseparatingforceseipConsequents y, the stresses which tend to Lseparate. the;tab s a e 7 b o bed; andd distnibuted Joy the curved-p011,- ioiis. ndieated; 1%13J3J1TT3L Naturally, twisti-n moyemernt of; either-section. aboutits Qwntaxisrand rel ive A to the,;j,ointris resisted by the extremely wide.. ran yer eleontactareaexistinglbetweentthe tabs andt a o perating: abutments,

In;Fi u1:e1-4,4a second-.embodiment this invention is i111 .1 st.11ate :1.. ;.This form- ;of the invention proyidesmany. oflthe advantageslofrthefirstform but; it issusceptihie to'inexnensive manufacturing teohni uessinee :thewstamping; .dies .used .to form the tabs areextremely simple. It will beobserved that ."the. .tab,j32';;oft section! 8 fisstraight -in cross Section-as; well ..as .longitudinal-lw a Moreover, @the b. 55.3 of erossarm 114x15 also; straightlinlcross sec.- tion'as wellgas longitudinally-.5.pHoivever the edge of tab 32 is upturned as at 34 to provide an abrupt lip which cooperates with the abutment formed between the tab and the body l8 to grasp tab 33 firmly. In this instance, the longitudinal side edges of tab 33 constitute the abutments which cooperate with the abutments of tab 32 to prevent angular displacement of the sections.

It will be apparent to those skilled in the art that the relative positions of the tabs can be reversed without departing from the spirit of this invention. For example in Figure 5, a joint is shown which is similar to the joint shown in Figure 2 except that the longitudinally dishshaped tab of base member I8 is curved downwardly and is superimposed upon tab of cross arm [4 which is dish-shaped in cross section. While the relative positions of the tabs are reversed, nevertheless the ears 35 and 36 of tab 3'! and the abutments 38 and 39 of tab 40 cooperate in much the same manner as they do in the previously described embodiment of Figure 2 to form a firm rigid joint. Other alterations of the basic struc ture shown in Figure 2 will be apparent to those skilled in the art. For example, the tab of the cross arm can be dish-shaped longitudinally, while the tab on the base member can be dishshaped in cross section. It will also be apparent that the embodiment shown in Figure 4 is also susceptible to a reversal of the relative positions of the tabs. In other words, the lower tab 32 can be superimposed on the top tab 33 and appropriately configurated to complement this tab if it is so desired.

Having described my invention, I claim:

1. A joint for two angularly disposed adjoining tubular sections comprising; a tab formed on each of said sections, one of said tabs being dishshaped longitudinally only and the other of said tabs being dish-shaped in cross section only and residing in nested relationship with said longitudinally dish-shaped tab, and means for detachably holding said tabs together in nested relationship.

2. A joint for angularly disposed adjoining tubular members comprising; a tab formed on each of said sections and projecting longitudinally therefrom, one of said tabs being configurated to provide two transversely extending abutments, said abutments being spaced to define a trough constituting a seat for the other tab therebetween, the other of said tabs residing in said seat and being configurated to provide two longitudinal abutments respectively engaging and cooperating with the abutments of the first tab to prevent angular displacement of said members relative to each other, and means for detachably holding said tabs together.

3. A joint for adjoining angularly disposed tubular members comprising; tabs formed on the ends of each member, one of said tabs having a pair of spaced abutments extending transversely thereof and the other of said tabs having a pair of spaced abutments extending longitudinally thereof, the abutments or" each tab engaging the abutments of the other tab in interlocking relationship to prevent angular displacement of the tubular members relative to each other, and means for detachably holding the tabs together.

4. A joint for adjoining angularly disposed tubular members comprising; tabs formed on the end of each member and extending lengthwise thereof, one of said tabs having a transversely extending edgewise lip and being configurated to rovide an abutment between the tab and the tubular body member and a substantially fiat seat for the other tab between the abutment and the lip, the other of said ta? 2.: being substantially flat and having two longitudinal edges respectively engaging the lip and abutment of the first tab to prevent angular displacement of the members relative to each other, and means detachably fastening the tabs together in seated interlocking relationship.

5. A joint for two adjoining tubular members comprising; a tab formed on each of said members, one of said tabs being configurated to provide two spaced abutments and a trough constituting a seat for the other tab between said abutments, said tab having a flat surface opposite to said tab seat, the other of said tabs adapted to reside within said seat and being configurated to provide a substantially flat central portion and a pair of abutments adjacent said flat portion and adapted to engage the abutments of the first tab to prevent angular displacement of said members relative to each other, bolts extending through said tabs and detachablylocking them together, said bolts having integral heads, nuts adapted to secure said bolts in position, said substantially flat portion of the second tab constituting a recessed, protected seat and the surface of said first tab opposite to said tab seat constituting a flat seat for said nuts and bolt heads.

ALLEN T. SHOTT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,408,907 Booth Oct. 8, 1946 FOREIGN PATENTS Number Country Date 184,246 Great Britain of 1922 

